[BP 7.0.2] MVCCPurger may stop running if doProceed check fails

The issue was spotted by Srinath.

Looking at the mvcc_purger code, I have a question.
case <-s.purgerCh:
            if time.Duration(time.Now().UnixNano()-lastPurgerTime) > purgerInterval {
                purgeRatio := s.GetStats().MVCCPurgeRatio                ctx := s.newWCtx()
                if s.Config.PurgeThreshold > 0 &&
                    purgeRatio > s.Config.PurgeThreshold &&
                    atomic.CompareAndSwapInt32(&s.isPurgerRunning, 0, 1) &&
                    doProceed(ctx)

{                    s.logInfo(fmt.Sprintf(“mvccPurger: starting... purge_ratio %.5f”, purgeRatio))                     s.PurgePages(s.Config.PurgeLowThreshold, ctx)                     purgeRatio = s.GetStats().MVCCPurgeRatio                     s.trySMRObjects(ctx, 0)                     s.logInfo(fmt.Sprintf(“mvccPurger: finished... purge_ratio %.5f”, purgeRatio))                     atomic.StoreInt32(&s.isPurgerRunning, 0)                 }

                s.releaseWCtx2(ctx)
                lastPurgerTime = time.Now().UnixNano()
            }if atomic.CompareAndSwapInt32(&s.isPurgerRunning, 0, 1)  succeeds and doProceed(ctx)  fails, we are not resetting isPurgerRunning to 0.  So, further calls to purge will not happen.